With the development of wireless communication systems, wireless communication systems are required to provide a wider variety of types and a larger quantity of services. In order to satisfy such a requirement, a broadband wireless communication system has appeared. Meanwhile, since a wireless communication system has a limited quantity of frequency resources, the broadband wireless communication system also has limited available frequency bands. Therefore, in order to provide a broadband service, it is necessary to increase available frequency bands.
FIG. 1 schematically illustrates a structure supporting a single frequency band and a structure supporting two frequency bands.
As a presumption before describing FIG. 1, a Base Station (BS) in a wireless communication system, especially in a broadband wireless communication system represented by an Institute of Electrical and Electronics Engineers (IEEE) 802.16 system, operates a single Frequency Assignment (FA) or at least two FAs. Further, the BS provides a wireless communication service to a Mobile Station (MS) through an FA operated by the BS itself.
Referring to FIG. 1, an MS 100 may move from an FA1 area 120 to an FA2 area 140. Here, the FA1 area 120 refers to a service area in which the MS 100 receives a wireless communication service using FA1, and the FA2 area 140 refers to a service area in which the MS 100 receives a wireless communication service using FA2.
At this time, when the MS 100 located within the FA1 area 120 can operate only one FA or when FA1 and FA2 are operated by different BSs, the MS 100 performs a handover between FA1 and FA2 and then receives a wireless communication service through FA2.
In contrast, when the MS 150 can operate at least two FAs or when at least two FAs are operated by a single BS, the MS 150 can receive a wireless communication service in both the FA1 area 160 and the FA2 area 180. The signal transmission and reception between the MS and the BS using multiple frequency bands as described above is advantageous in transmitting and receiving high speed and large capacity data.
However, there has been no procedure promised between an MS and a BS in order to use multiple frequency bands. Further, there has been no supporting scheme for enabling data transmission/reception through a second sub-band when an MS and a BS have failed in transmitting and receiving a first sub-band preparation indicator indicating that the MS and the BS have been completely prepared to transmit and receive data through the first sub-band. Moreover, there has been no scheme for notifying a BS that an MS can transmit and receive data using multiple frequency bands.